Various types of biometric systems are used more and more in order to provide for increased security and/or enhanced user convenience.
In particular, fingerprint sensing systems have been adopted in, for example, consumer electronic devices, thanks to their small form factor, high performance, and user acceptance.
Among the various available fingerprint sensing principles (such as capacitive, optical, thermal etc.), capacitive sensing is most commonly used, in particular in applications where size and power consumption are important issues.
All capacitive fingerprint sensors provide a measure indicative of the capacitance between each of several sensing structures and a finger placed on or moved across the surface of the fingerprint sensor.
One popular fingerprint detection methodology is based on an induced potential difference between a finger placed on the sensor and an underlying capacitive sensing structure. The potential difference may be induced by providing a time varying drive signal to the finger, to a common ground plane, to all or parts of the fingerprint sensor, and combinations thereof. Accordingly, this results in an electromagnetic environment influenced by a time varying potential.
Fingerprint sensors are integrated in an increasing range of various electronic devices which may comprise many different types of components. In some cases, the drive signal, which may be generated by the fingerprint sensor or by a separate device arranged along the fingerprint sensor, may disturb or interfere with the operation of other sensitive components.
Accordingly, there is a need to provide an improved method and system for providing a drive signal for a fingerprint sensing device.